Don't look at the roller coaster, look at your game.
You say you've been stagnant for months.
Are you playing the same games and limits that you were before becoming stagnant? If not, go back to where you were and try to get back on a winning streak, if nothing else but to build your bankroll and get back some confidence.
If your bankroll is stagnant and you're playing the same games, then you really need to figure out how your game has changed and fix it. If you have PokerTracker, that could be a big help.
If you're jumping around between dollar levels, MTTs, single table SNGs, and multi table SNGs, remember that each type and each level play differently and require adjustments. Pick the one or two that you are the most comfortable with and see if you can establish yourself at that level. Also, don't play at a level higher than your bankroll justifies.
It really comes down to confidence. Find something you can win at and carefully move forward from there.
Good luck.